The U.S. Department of Justice did not mislead a court and attempt to entrap file storage site Megaupload on copyright infringement charges, the agency said in a new filing in the case.

Megaupload's charges that the DOJ conspired to entrap the site on criminal copyright charges are "baseless," an official with the U.S. Attorney's Office for the Eastern District of Virginia wrote in a court document filed Friday. Earlier this month, Megaupload filed court documents saying that in 2010 the DOJ asked the site, through its hosting vendor, to keep infringing files as part of a DOJ investigation, then later charged Megaupload with copyright infringement.

But the search warrant contains no request for Megaupload to keep files, Assistant U.S. Attorney Andrew Peterson wrote in the DOJ's Friday filing. "Megaupload does not cite a single communication between the government and Megaupload or a single instruction from any member of the government to Megaupload; there are none," Peterson wrote.

The DOJ also did not mislead the district court by inserting new information into affidavits related to the Megaupload charges, as Megaupload has claimed, Peterson wrote.

Megaupload lawyer Ira Rothken pointed to a portion of the June 2010 search warrant targeting Carpathia Hosting, Megaupload's hosting provider. U.S. Immigration and Customs Enforcement (ICE) asked a judge to seal the search warrant affidavit because disclosure could "provide an opportunity to destroy evidence [and] change patterns of behavior."

The search warrant also asked Carpathia and Megaupload to assist in the copyright infringement investigation.

"The government cannot, on one hand, tell a U.S. court under penalty of perjury in seeking the cooperation of Megaupload in a search warrant they wanted to prevent evidence destruction of alleged infringing content files, and then, on the other hand, complain to a different court under penalty of perjury that Megaupload is a criminal for not destroying such files," Rothken said in an email.

After ICE asked Megaupload to cooperate in an investigation, the site was obligated to keep evidence, Rothken added.

"If the U.S. changed their mind at some point they could have written Megaupload a letter but they didn't," he added. "Instead the U.S. apparently used Megaupload's honorable compliance with the government's cooperation request to concoct a takedown of the entire Megaupload site by domain name seizure."

The DOJ, in its Friday filing, opposed Megaupload's request to file a new brief regarding its accusations that the DOJ conducted an improper search of its servers. It also opposed Megaupload's request to file a motion to unseal the search warrant materials, with the DOJ saying the materials are already unsealed.

Grant Gross covers technology and telecom policy in the U.S. government for The IDG News Service. Follow Grant on Twitter at GrantGross. Grant's e-mail address is grant_gross@idg.com.